In Plan 9, each M is implemented as a separate OS process with
its own working directory. To keep the wd consistent across
goroutines (or rescheduling of the same goroutine), CL 6350
introduced a Fixwd procedure which checks using getwd and calls
chdir if necessary before any syscall operating on a pathname.
This wd checking will not be necessary if the pathname is absolute
(starts with '/' or '#'). Getwd is a fairly expensive operation
in Plan 9 (implemented by opening "." and calling Fd2path on the
file descriptor). Eliminating the redundant getwd calls can
significantly reduce overhead for common operations like
"dist test --list" which perform many syscalls on absolute pathnames.
Updates #9428.
Change-Id: I13fd9380779de27b0ac2f2b488229778d6839255
Reviewed-on: https://go-review.googlesource.com/97675
Reviewed-by: David du Colombier <0intro@gmail.com>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Run-TryBot: David du Colombier <0intro@gmail.com>
On Plan 9, the underlying create() syscall with DMDIR flag, which is
used to implement Mkdir, will fail silently if the path exists and
is not a directory. Work around this by checking for existence
first and rejecting Mkdir with error EEXIST if the path is found.
Fixes#23918
Change-Id: I439115662307923c9f498d3e7b1f32c6d205e1ad
Reviewed-on: https://go-review.googlesource.com/94777
Reviewed-by: David du Colombier <0intro@gmail.com>
syscall.Exit and runtime.exit do the same thing.
Why duplicate code?
CL 45115 fixed bug where windows runtime.exit was correct,
but syscall.Exit was broken. So CL 45115 fixed windows
syscall.Exit by calling runtime.exit.
Austin suggested that all OSes should do the same, and
this CL implements his idea.
While making changes, I discovered that nacl syscall.Exit
returned error
func Exit(code int) (err error)
and I changed it into
func Exit(code int)
like all other OSes. I assumed it was a mistake and it
is OK to do because cmd/api does not complain about it.
Also I changed plan9 runtime.exit to accept int32 just
like all other OSes do.
Change-Id: I12f6022ad81406566cf9befcc6edc382eebd413b
Reviewed-on: https://go-review.googlesource.com/66170
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: David du Colombier <0intro@gmail.com>
Last runtime use was removed in https://golang.org/cl/133700043,
September 2014.
Replace plan9 syscall uses with plan9-specific variable.
Change-Id: Ifb910c021c1419a7c782959f90b054ed600d9e19
Reviewed-on: https://go-review.googlesource.com/55450
Reviewed-by: Martin Möhrmann <moehrmann@google.com>
Run-TryBot: Martin Möhrmann <moehrmann@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Delete use stub from asm.s, leaving only a dummy file.
Deleting the file causes Windows build to fail.
Fixes#16607
Change-Id: Ic5a55e042e588f1e1bc6605a3d309d1eabdeb288
Reviewed-on: https://go-review.googlesource.com/36716
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
syscall.Getpagesize currently returns hard-coded page sizes on all
architectures (some of which are probably always wrong, and some of
which are definitely not always right). The runtime now has this
information, queried from the OS during runtime init, so make
syscall.Getpagesize return the page size that the runtime knows.
Updates #10180.
Change-Id: I4daa6fbc61a2193eb8fa9e7878960971205ac346
Reviewed-on: https://go-review.googlesource.com/25051
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviving earlier work by @ality in https://golang.org/cl/57890043
to make the closing of extra file descriptors in syscall.StartProcess
less race-prone. Instead of making a list of open fds in the parent
before forking, the child can read through the list of open fds and
close the ones not explicitly requested. Also eliminate the
complication of keeping open any extra fds which were inherited by
the parent when it started.
This CL will be followed by one to eliminate the ForkLock in plan9,
which is now redundant.
Fixes#5605
Change-Id: I6b4b942001baa54248b656c52dced3b62021c486
Reviewed-on: https://go-review.googlesource.com/22610
Run-TryBot: David du Colombier <0intro@gmail.com>
Reviewed-by: David du Colombier <0intro@gmail.com>
In CL 6350, Brad fixed the following system calls
to use the program-wide workding directory:
- bind
- chdir
- create
- open
- remove
- stat
- umount
- wstat
However, Russ Cox pointed out that the mount
system call should be fixed as well.
Change-Id: I6139ed11ba449f18c46e95269f4d0e51be7cec48
Reviewed-on: https://go-review.googlesource.com/6385
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
On Plan 9, the pwd is apparently per-thread not per process. That
means different goroutines saw different current directories, even
changing within a goroutine as they were scheduled.
Instead, track the the process-wide pwd protected by a mutex in the
syscall package and set the current goroutine thread's pwd to the
correct once at critical points.
Fixes#9428
Change-Id: I928e90886355be4a95c2be834f5883e2b50fc0cf
Reviewed-on: https://go-review.googlesource.com/6350
Reviewed-by: David du Colombier <0intro@gmail.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Given:
p := alloc()
fn_taking_ptr(p)
p is NOT recorded as live at the call to fn_taking_ptr:
it's not needed by the code following the call.
p was passed to fn_taking_ptr, and fn_taking_ptr must keep
it alive as long as it needs it.
In practice, fn_taking_ptr will keep its own arguments live
for as long as the function is executing.
But if instead you have:
p := alloc()
i := uintptr(unsafe.Pointer(p))
fn_taking_int(i)
p is STILL NOT recorded as live at the call to fn_taking_int:
it's not needed by the code following the call.
fn_taking_int is responsible for keeping its own arguments
live, but fn_taking_int is written to take an integer, so even
though fn_taking_int does keep its argument live, that argument
does not keep the allocated memory live, because the garbage
collector does not dereference integers.
The shorter form:
p := alloc()
fn_taking_int(uintptr(unsafe.Pointer(p)))
and the even shorter form:
fn_taking_int(uintptr(unsafe.Pointer(alloc())))
are both the same as the 3-line form above.
syscall.Syscall is like fn_taking_int: it is written to take a list
of integers, and yet those integers are sometimes pointers.
If there is no other copy of those pointers being kept live,
the memory they point at may be garbage collected during
the call to syscall.Syscall.
This is happening on Solaris: for whatever reason, the timing
is such that the garbage collector manages to free the string
argument to the open(2) system call before the system call
has been invoked.
Change the system call wrappers to insert explicit references
that will keep the allocations alive in the original frame
(and therefore preserve the memory) until after syscall.Syscall
has returned.
Should fix Solaris flakiness.
This is not a problem for cgo, because cgo wrappers have
correctly typed arguments.
LGTM=iant, khr, aram, rlh
R=iant, khr, bradfitz, aram, rlh
CC=dvyukov, golang-codereviews, r
https://golang.org/cl/139360044
